(1) Field of the Invention
This invention relates to a resin composition having a good antistatic property and heat resistance, which comprises a specific methacrylimide group-containing polymer, and incorporated therein, a specific polyhydric alcohol compound and/or a compound having polyoxyethylene segments.
(2) Description of the Related Art
A methacrylimide group-containing polymer has a good heat resistance and transparency, a relatively high heat distortion temperature, a good rigidity, surface hardness, and molding processability, but this polymer has a problem in that the electric resistance value is large and the polymer is easily statically charged by for example, rubbing or peeling.
A method of an internal kneading of an antistatic agent is generally adopted for imparting an antistatic property to plastics, and in this method, an antistatic agent having a good compatibility with a base resin must be selected. If an antistatic agent having a poor compatibility with the base resin is used, problems such as a sticky surface and the precipitation of a white powder are caused by an excessive migration or bleeding of the antistatic agent to the surface, and furthermore, the inherent transparency of the resin becomes poor. In contrast, if an antistatic agent having a good compatibility with the base resin is used, the antistatic agent is uniformly dispersed in the resin, and a substantial antistatic effect is not manifested.
A methacrylimide group-containing polymer has a relatively high glass transition temperature, and therefore, a migration of an antistatic agent to the surface becomes more difficult. Moreover, since the molding temperature of this polymer is high, the antistatic agent per se must have a high heat stability.
Namely, appropriate antistatic agents must be developed for respective base resins, but an antistatic agent effective for the methacrylimide group-containing polymer has not been developed.
A resin composition comprised of a methacrylimide group-containing polymer and a fatty acid glyceride ester is described in Japanese Unexamined Patent Publication No. 64-75290. It is taught that this resin composition has an improved moldability as compared with a methacrylimide group-containing polymer, but this publication is silent on the antistatic property thereof.
A resin material having an antistatic property and a good heat resistance has not been known, and a development of this resin material is required.